Pinaceae (Pinus)
Pinus (ponderosa)
Pinaceae
Pinus
ponderosa
Ponderosa Pine
pinpon
plants
seed
Bareroot (field grown)
2+0
21 Months
Generally clients on west side of Cascades order a larger seedling with minimum height of 6 inches (15cm) and 5 mm caliper while east of the Cascade clients order smaller trees with minimum heights of 4 inches (10cm) and 4 millimeter caliper. Root system must balance top growth. But this is less likely with the taller trees especially if root pruning is requested at 8 to 10 inches. No mechanical damage on the main stem. Cranberry girdler damage is acceptable if it is less than 0.6cm (¬") long by ¬ the circumference of the stem.
Most seed comes from wild collections, with the remainder coming from seed orchards managed by the Forest Service and Bureau of Land Management. All seed is kept separate by the collection area, elevation and date collected. All seed is collected or contracted for collection by the Forest Service and Bureau of Land Management or other government agencies. All seed is collected in the fall.
Seed is sent to Bend Pine Extractory in the fall for cleaning. It is dried to between 5 and 8% moisture and placed in air tight plastic bags, then stored in seed freezers set at -15C (5F) at the nursery. This seed has a long storage life under these conditions.
Seed is placed in mesh bags and soaked in cold running water for 48 hour. The seed is then laid out 3cm (1 in) thick on trays with fine screen meshed bottoms and placed in cold stratification rooms for 30 to 45 days. Rooms are equipped with foggers to keep the naked seed moist at all times (seed covered with free moisture). Temperatures are set at 1C (33F). Seed is monitored daily to detect seed mold. If mold is found, the seed is hosed down with water.
The nursery soils are a sandy loam (Central Point Sandy Loam Soil Series - Coarse-loamy, mixed, mesic Pachic Haploxeroll). Nine months before sowing, in late spring, 2.5cm (1in) inch of fresh sawdust is applied and disked into the surface. During the summer, the fields are irrigated to encourage weeds to sprout. The fields are disked at regular intervals to keep them free of weeds. The addition of sawdust, weed free fields and early sow of seed keeps the incidence of disease and weeds to a minimum and this is the reason we will not be fumigating our fields this year. We will however, be using a pre-emergence herbicide.
Seeds are sown in late March to early April. The seed is sown through a modified Oyjard seed drill. Seed is sown for an initial density of 237 seedlings/m2 (22 seedlings/ft2). Attached to the front of the seed drill is a fertilizer bander. Depending on our soil analysis the bander places 500 kg/ha (450 lb/ac) of potassium sulfate (0-0-53) and 400 kg/ha (360 lb/ac) of ammonium phosphate (11-52-0) is placed at a depth in the soil of 10cm (4in). The seed drill has been adapted by attaching 8 steel bands to the drum. The bands are 3cm (1¬ in) wide by 1cm (3/8in) deep and 15cm (6 in) apart. As it rolls in front of the seeder, the band creates a small impression for the seed to drop into. The tubes of the seed drill have been increased in size to allow large seed to pass through and drop directly into the impressions. Behind the seed tubes are small wheels that press the seed into the surface of the soil. Within a half hour of sowing, and then covered with 1cm to 1.3cm (3/8 to « in) of fresh (undecomposed) sawdust. The sawdust is sprayed with Agrilock at 15% solution to hold it in place in case of high winds. Then the seedbeds are sprayed with Goal (oxyfluorfen) at 2 pints per acre as a pre-emergent control for weeds.The seedbeds are irrigated when the seed appears to be drying out. This occurs only on warm days. There is no fertilization during this period.
3 Weeks
FIRST YEAR Irrigation: Soil tensiometers are placed at 15cm (6in) depths and monitored at least once per week. Soils are irrigate to 30cm (12in) when tensions are at -0.5 or higher. Light (5 minute) bursts of irrigation are given when surface soil temperatures (temperature probe placed under a ¬ inch of soil) are 33C (91F) in June; 35C (95F) in July; 38C (100F) in early August and 40C (104F) in mid August. Fertilizer: Fertilizer is applied in granular form over the seedlings. After application is complete, the fertilizer is washed off the foliage and into the soil with a half hour of irrigation water. Four applications are made: Approximately 6 weeks after emergence, 56 kg/ha (50 lbs/ac) of ammonium nitrate is applied when lateral roots have developed from new germinants. 8 weeks after emergence - 84 kg/ha (75 lbs/ac of ammonium nitrate. 10 weeks after emergence - 134 kg/ha (120 lbs/ac) ammonium sulfate and 12 weeks after emergence - 112 ka/ha (100 lbs/ac) of ammonium nitrate.IPM: Handweeding of beds if necessary. SECOND YEAR Irrigation: Starting last week of March, irrigate soil profile when soil tension is -0.3 bars. Irrigate to cool seedlings when foliar temperatures reach 32C (90F) from April to mid June, 35C (95F) from mid June through July, 38C (100F) early August and 40C (105F) from late August on .Fertilizer: The first application of ammonium nitrate at 168 kg/ha(150 lbs/ac) is applied two weeks before bud break (end of March). Two weeks later 224 kg/ha (200 lbs/ac) of ammonium sulfate is applied and followed two weeks later with 84 kg/ha (75 lbs/ac) of ammonium nitrate. IPM: Hand weeding. If Crysoteuchia topiaria (cranberry girdler) exceeds threshold (which does not happen every year) then the bug vacuum is used to reduce the moth population. If the populations are still high, then pydrin at 5.3 oz/acre is used to control the moths. If high levels of seedling damage is detected in the summer months, then an application of Dursban will be considered. Prunes and wrenches: Vertically pruned in the spring to 15cm (6in) and immediately wrenched at 30cm (12in). 4 to 6 wrenches during the growing season. Top prune seedlings at 30cm (12 in) when 15 percent of the seedlings are at or above 30cm (12 in). Top prune a second time at 43cm (17in) when 10 percent of the seedlings are at or above 43cm (17 in).
FIRST YEAR
By the third week in August or when the seedlings dormancy is induced. Irrigation: Only irrigate when the surface temperatures exceed 38C (100F) or pre-dawn plant moisture stress (PMS) exceeds 10 bars. In the early fall the soil profile is completely moistened and plants are kept below 5 bars pre-dawn PMS. From October through the early portion of November, the seedlings are protected from frosts through irrigation. Fertilizer: No fertilizations. IPM: Handweed beds ifneeded. Prunes and wrenches: Seedlings are horizontally pruned at 15cm (6 in) in September and immediately wrenched at 30cm (12in).
SECOND YEAR
When 80 percent of the seedlings reach 25cm (10 in), dormancy is induced. Irrigation: Starting in June irrigate soil profile when pre-dawn PMS is 12 bars. In mid September, the soil profile is irrigated. From that point forward, the profile is irrigated when tensiometers read -0.3 to -0.5 bars.Fertilizer: No fertilizations. IPM: Handweed beds of needed. Prunes and wrenches: Wrenched at 30cm (12in) in mid Sept for root growth.
Lifting window is January through early February. Seedlings are hand-lifted after the seedlings beds have been undercut using an Lundeby lifter. Lifting conditions must be in unsaturated soils, PMS below 15 bars and temperatures above -3C (27F). Seedlings are stored at 1C (33F) and 100 percent humidity for 1 to 5 days before sorting. Sorting removes seedlings that do not meet target specifications (see above). Many clients ask for seedlings to be rootpruned between 23 and 30cm (9 and 12 inch) for planting reasons. We accomplish this with paper cutters. At clients request, we will place a rubber band around a group of seedlings, usually 25. Seedlings are placed in 3 ply bags and sown shut. The bags are placed on racks and stored in coolers at 1C (33F) for storage durations less than 2 months or in freezers at -1C (29F) for greater than 2 months.
Up to 5 months
Schopmeyer C.S. 1974. Seeds of Woody Plants in the United States. Ag Handbook 450. USDA Forest Service.
Duryea M.L., Landis T.D. 1984. Forest Nursery Manual: Production of Bareroot Seedlings. Martius Nijhoff/Dr W. Junk Publishers, the Hague Boston/Lancaster, Forest Research Lab, OSU Corvallis. 386p.
Steinfeld, David E. 2001. Propagation protocol for production of Bareroot (field grown) Pinus ponderosa plants 2+0; USDA FS - J Herbert Stone Nursery Central Point, Oregon. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/05/01). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.
